The present invention relates to a film feed control apparatus of a still camera, and more particularly, to a film feed control apparatus of a still camera having a mechanism for detecting information concerning a film provided on a film, a film magazine, a film cassette or a film cartridge.
In still cameras in which a film must be rewound when the film from a film feed chamber has been wound and exposed, some cameras are known to have a film rewinding mechanism for automatically rewinding a film after exposure of a roll of the film is completely finished.
Various types of cameras having such a mechanism are conventionally known. For example, one type of camera having a timer for measuring a time while a film wind motor is enabled is known. In this camera, when the wind motor is not disabled after a predetermined time necessary for winding a unit length (e.g., a frame or a pitch of perforations) of a film is exceeded, the film rewind operation is automatically started. This is generally caused when a rotation of the motor is prevented during film winding and the rotation velocity thereof is decreased, or when the total length of a film to be taken up from a film cartridge, for example, has been wound and the rotation of the motor is thereby stopped.
In another type of a camera which detects a current which flows into a motor, when an excessive current flows into the motor, the film rewind operation is automatically started. An excessive current flow to the motor is caused when the motor is forcibly stopped during its ON period. This may be caused when the total length of the film to be taken up from a film magazine has been wound as described above.
However, in both types of cameras, another reason preventing the rotation of the motor is plausible. For example, when the temperature is low, a battery voltage is lowered, thereby prolonging a time necessary for winding a frame of a film. For this reason, the former type of camera has a problem in that the film rewind operation is started even if an unexposed frame of film remains in the film magazine.
For example, when a film, film maganize, cassette or cartridge has a malfunction and the wind operation is not smoothly performed, the rotation of the motor is temporarily stopped. In this case, in the latter type of camera, a current flowing to the motor temporarily becomes excessive and the film rewind operation is thereby started.
Still another type of a camera is known wherein the number of film frames exposed is counted when wound by a winding device, and when the counted number reaches a nominal number of exposures guaranteed for the film, the film rewind operation is automatically started regardless of the condition of the wound film. However, a film generally has an extra length for two or three exposures in addition to the nominal number of exposures. In this case, in a camera of this type, only exposures of a nominal number can be performed, but additional exposures as described above cannot be performed.